The present invention pertains to machines for filling cans with solid pack tuna. More particularly, the present invention provides a significant improvement to a widely used, prior art tuna canning machine known today as the “Luthi SP” canning machine. The “Luthi SP” machine is currently manufactured by the assignee of this application, Atlas Pacific Engineering Company, and is shown and described in U.S. Pat. No. 4,116,600, incorporated herein by reference.
The Luthi SP machine is capable of filling two cans simultaneously. An inherent disadvantage to that machine is that, without the benefit of the present invention, only one-half of the filled cans have the freshly cut cake surface at the top of the can. The other one-half of the filled cans have the freshly cut cake surface at the bottom of the can. The disadvantage of having the freshly cut cake surface at the bottom of half the cans is that those cans are downgraded, as described below, at significant cost to the canner. The present invention, as described below, overcomes the problem and achieves the result of every filled can having the freshly cut cake surface at the top of the can.
The perceived quality of the canned tuna is based primarily on what the customer sees at the top of the can when it is opened. As noted in the '600 patent, referenced above, the best quality of solid pack tuna is when the fish is packed with the grain being vertical, and with minimum amount of fragments and floating particles at the top of the can. It has been known that the premium tuna cake appearance is achieved at the “cut cake surface,” referring to that surface created by a knife which cuts a “plug” into two, can sized “cakes.” However, until the present invention, it has not been realized how to achieve a “cut cake surface” at the top of every can. The need for consistent premium cake appearance has existed since at least 1978, the date of the '600 patent. Certain markets for canned tuna today demand a consistent premium cake appearance. The applicant is unaware of any solution, other than the present invention, to the problem of presenting a “cut cake surface” at the top of every can of solid pack tuna wherein at least two cans are filled simultaneously by a single machine.
The solution provided by the present invention is elegant in its simplicity. Whereas the prior art would slice a tuna plug into two can sized cakes along a planar surface A-A, and then transfer both cakes with two knock-out plungers positioned on the same side of planar surface A-A into two cans positioned on the opposite side of planar surface A-A, the present invention transfers the cakes into two cans positioned on opposite sides of planar surface A-A with knock-out plungers each located on opposite sides of planar surface A-A. This solution has escaped those skilled in the art since at least 1978, some 30 years!! In addition to solving the above stated problem, the present invention may be relatively easily retrofitted onto pre-existing Luthi SP machines! Indeed, as shown and described below, the present invention is described as applied to Luthi SP machines, but is applicable to similarly designed tuna packing machines available from other suppliers.
A primary object of the present invention is to provide an apparatus and method for canning solid pack tuna wherein a premium cake appearance is achieved in every can.
A further object of the invention is to provide an apparatus that may be readily retrofitted onto existing, prior art tuna canning machines to provide a premium cake appearance in every can rather than in only half the cans.
Other objects and advantages will become apparent from the following description and the drawings.